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**Atomic Electron Configurations and Chemical Periodicity**

Chapter 8 Atomic Electron Configurations and Chemical Periodicity Dr. S. M. Condren

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**ATOMIC ELECTRON CONFIGURATIONS AND PERIODICITY**

Dr. S. M. Condren

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Atomic Orbitals Types of orbitals found in the known elements: s, p, d, and f schools play defensive football Packer version: secondary pass defense fails Dr. S. M. Condren

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**Atomic Orbitals Shapes s – spherical p – dumbbell d – complex**

f – very complex Dr. S. M. Condren

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**Arrangement of Electrons in Atoms**

Electrons in atoms are arranged as SHELLS (n) SUBSHELLS (l) ORBITALS (ml) Dr. S. M. Condren

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**Arrangement of Electrons in Atoms**

Each orbital can be assigned no more than 2 electrons! This is tied to the existence of a 4th quantum number, the electron spin quantum number, ms. Dr. S. M. Condren

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**Electron Spin Quantum Number, ms**

Can be proved experimentally that electron has a spin. Two spin directions are given by ms where ms = +1/2 and -1/2. Dr. S. M. Condren

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**Electron Spin and Magnetism**

Diamagnetic: NOT attracted to a magnetic field Paramagnetic: substance is attracted to a magnetic field. Substances with unpaired electrons are paramagnetic. Dr. S. M. Condren

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**Measuring Paramagnetism**

Paramagnetic: substance is attracted to a magnetic field. Substance has unpaired electrons. Diamagnetic: NOT attracted to a magnetic field Dr. S. M. Condren Active Figure 8.2

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**QUANTUM NUMBERS Now there are four! n ---> shell 1, 2, 3, 4, ...**

l ---> subshell 0, 1, 2, ... n - 1 ml ---> orbital -l l ms ---> electron spin +1/2 and -1/2 Dr. S. M. Condren

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**Pauli Exclusion Principle**

No two electrons in the same atom can have the same set of 4 quantum numbers. That is, each electron has a unique address. Dr. S. M. Condren

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**Electrons in Atoms When n = 1, then l = 0**

this shell has a single orbital (1s) to which 2e- can be assigned When n = 2, then l = 0, 1 2s orbital e- three 2p orbitals 6e- TOTAL = 8e- Dr. S. M. Condren

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**Electrons in Atoms When n = 3, then l = 0, 1, 2 3s orbital 2e-**

three 3p orbitals 6e- five 3d orbitals 10e- TOTAL = e- Dr. S. M. Condren

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**Electrons in Atoms When n = 4, then l = 0, 1, 2, 3 4s orbital 2e-**

three 4p orbitals 6e- five 4d orbitals 10e- seven 4f orbitals 14e- TOTAL = 32e- And many more! Dr. S. M. Condren

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Dr. S. M. Condren

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**Assigning Electrons to Atoms**

Electrons generally assigned to orbitals of successively higher energy. For H atoms, E = - C(1/n2). E depends only on n. For many-electron atoms, energy depends on both n and l. Dr. S. M. Condren

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**Electron Filling Order**

Dr. S. M. Condren

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LED Traffic Lights Chapter 7, Problem 3, page 326 text Dr. S. M. Condren

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**Writing Atomic Electron Configurations**

Two ways of writing configs. One is called the spdf notation. 1 s value of n value of l no. of electrons spdf notation for H, atomic number = 1 Dr. S. M. Condren

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**Writing Atomic Electron Configurations**

Other is called the orbital box notation One electron has n = 1, l = 0, ml = 0, ms = + 1/2 Other electron has n = 1, l = 0, ml = 0, ms = - 1/2 Dr. S. M. Condren

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**See “Toolbox” on CD for Electron Configuration tool.**

Dr. S. M. Condren

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**Electron Configurations and the Periodic Table**

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**Lithium Group 1A Atomic number = 3 1s22s1 ---> 3 total electrons**

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**Beryllium Group 2A Atomic number = 4 1s22s2 ---> 4 total electrons**

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**Boron Group 3A Atomic number = 5 1s2 2s2 2p1 ---> 5 total electrons**

Dr. S. M. Condren

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**Carbon Group 4A Atomic number = 6 1s2 2s2 2p2 --->**

6 total electrons Here we see for the first time HUND’S RULE. When placing electrons in a set of orbitals having the same energy, we place them singly as long as possible. Dr. S. M. Condren

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**Nitrogen Group 5A Atomic number = 7 1s2 2s2 2p3 --->**

7 total electrons Dr. S. M. Condren

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**Oxygen Group 6A Atomic number = 8 1s2 2s2 2p4 --->**

8 total electrons Dr. S. M. Condren

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**Fluorine Group 7A Atomic number = 9 1s2 2s2 2p5 --->**

9 total electrons Dr. S. M. Condren

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**Neon Group 8A Atomic number = 10 1s2 2s2 2p6 --->**

10 total electrons Note that we have reached the end of the 2nd period, and the 2nd shell is full! Dr. S. M. Condren

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**Sodium Group 1A Atomic number = 11 1s2 2s2 2p6 3s1 or**

“neon core” + 3s1 [Ne] 3s1 (uses rare gas notation) Note that we have begun a new period. All Group 1A elements have [core]ns1 configurations. Dr. S. M. Condren

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**Aluminum Group 3A Atomic number = 13 1s2 2s2 2p6 3s2 3p1 [Ne] 3s2 3p1**

All Group 3A elements have [core] ns2 np1 configurations where n is the period number. Dr. S. M. Condren

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**Phosphorus Group 5A Atomic number = 15 1s2 2s2 2p6 3s2 3p3**

Yellow P Red P Group 5A Atomic number = 15 1s2 2s2 2p6 3s2 3p3 [Ne] 3s2 3p3 All Group 5A elements have [core ] ns2 np3 configurations where n is the period number. Dr. S. M. Condren

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**Calcium Group 2A Atomic number = 20 1s2 2s2 2p6 3s2 3p6 4s2 [Ar] 4s2**

All Group 2A elements have [core]ns2 configurations where n is the period number. Dr. S. M. Condren

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**Transition Metals Table 8.4**

All 4th period elements have the configuration [argon] nsx (n - 1)dy and so are d-block elements. Chromium Iron Copper Dr. S. M. Condren

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**Transition Element Configurations**

3d orbitals used for Sc-Zn (Table 8.4) Dr. S. M. Condren

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Dr. S. M. Condren

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**Board Work V – electron configuration Cr – electron configuration**

Mn – electron configuration Ni – electron configuration Cu – electron configuration Zn – electron configuration Dr. S. M. Condren

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**Magnetism Paramagnetism Ferromagnetism**

Spins are randomized by thermal energy. Spins are aligned with or against an applied magnetic field. Ferromagnetism Spins are aligned with an applied magnetic field. Spins are ordered in magnetic domains. Dr. S. M. Condren

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**NMR and MRI http://mrsec.wisc.edu/Edetc/background/NMR/index.html**

Nuclei also have spin and nuclear quantum numbers 800 MHz, 18.8 T NMR spectrometer Open Magnet Design MRI Dr. S. M. Condren

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Memory Metal Dr. S. M. Condren

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Nitinol, NiTi Dr. S. M. Condren

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**Lanthanides and Actinides**

All these elements have the configuration [core] nsx (n - 1)dy (n - 2)fz and so are f-block elements. Cerium [Xe] 6s2 5d1 4f1 Uranium [Rn] 7s2 6d1 5f3 Dr. S. M. Condren

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**Lanthanide Element Configurations**

4f orbitals used for Ce - Lu and 5f for Th - Lr (Table 8.2) Dr. S. M. Condren

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Dr. S. M. Condren

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Ion Configurations To form cations from elements remove 1 or more e- from subshell of highest n [or highest (n + l)]. P [Ne] 3s2 3p e > P3+ [Ne] 3s2 3p0 Dr. S. M. Condren

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Ion Configurations For transition metals, remove ns electrons and then (n - 1) electrons. Fe [Ar] 4s2 3d6 loses 2 electrons ---> Fe2+ [Ar] 4s0 3d6 To form cations, always remove electrons of highest n value first! Dr. S. M. Condren

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Quantum Numbers What is one of the sets of quantum numbers for the 4s electrons in calcium? n = 4; l = 0; ml = 0; s = +1/2 or n = 4; l = 0; ml = 0; s = -1/2 Dr. S. M. Condren

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Quantum Numbers What is one of the sets of quantum numbers for the 3p electrons in sulfur? n = 3; l = 1; ml = +1; s = +1/2 or n = 3; l = 1; ml = +1; s = -1/2 or n = 3; l = 1; ml = 0; s = +1/2 or n = 3; l = 1; ml = 0; s = -1/2 or n = 3; l = 1; ml = -1; s = +1/2 or n = 3; l = 1; ml = -1; s = -1/2 Dr. S. M. Condren

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Quantum Numbers What is one of the sets of quantum numbers for the 3d electrons in Fe? n = 3; l = 2; ml = +2; s = +1/2 or n = 3; l = 2; ml = +2; s = -1/2 or n = 3; l = 2; ml = +1; s = +1/2 or n = 3; l = 2; ml = +1; s = -1/2 or n = 3; l = 2; ml = 0; s = +1/2 or n = 3; l = 2; ml = 0; s = -1/2 or n = 3; l = 2; ml = -1; s = +1/2 or n = 3; l = 2; ml = -1; s = -1/2 or n = 3; l = 2; ml = -2; s = +1/2 or n = 3; l = 2; ml = -2; s = -1/2 Dr. S. M. Condren

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**Announcements You may bring a 4x6 index card with information**

A periodic table and a table of thermodynamic data will be furnished. You need to know your TAs name and your section number. Photo ID will be required when submitting your exam. Dr. S. M. Condren

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**Announcements General Chemistry 103 Hour Exam 2 Nov. 6, 2006**

Teaching Assistant _________________________ Section _____ Name _________________________________ c General Chemistry 103 Hour Exam 2 Nov. 6, 2006 ALL WORK MUST APPEAR ON TEST FOR ANY CREDIT. Work includes “stating the question in a mathematical form.” A box should be drawn around the answer to be graded for a problem. Dr. S. M. Condren

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**Announcements Last day to drop**

Suzie and Christie have papers to return, please see them after class Dr. S. M. Condren

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**Bonus Points Exam II – worth 105 points, count as 100**

5 pts - Available through “Other Lecture Documents” this week, due Friday Nov. 10 Exam III – worth 105 points, count as 100 5 pts - Available through “Other Lecture Documents” later, due Friday Dec. 15 Dr. S. M. Condren

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**Ion Configurations How do we know the configurations of ions?**

Determine the magnetic properties of ions. Sample of Fe2O3 Sample of Fe2O3 with strong magnet Dr. S. M. Condren

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**General Periodic Trends**

Atomic and ionic size Ionization energy Electron affinity Higher effective nuclear charge Electrons held more tightly Larger orbitals. Electrons held less tightly. Dr. S. M. Condren

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**Effective Nuclear Charge, Z***

Atom Z* Experienced by Electrons in Valence Orbitals Li Be B C N O F Increase in Z* across a period [Values calculated using Slater’s Rules] Dr. S. M. Condren

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**Orbital Energies Orbital energies “drop” as Z* increases**

Dr. S. M. Condren

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Atomic Radii Dr. S. M. Condren

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**Atomic Size Size goes UP on going down a group.**

Because electrons are added further from the nucleus, there is less attraction. Size goes DOWN on going across a period. Dr. S. M. Condren

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**Atomic Radius Increase in Z***

Size decreases across a period owing to increase in Z*. Each added electron feels a greater and greater + charge. Large Small Increase in Z* Dr. S. M. Condren

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Trends in Atomic Size Dr. S. M. Condren

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**Sizes of Transition Elements**

3d subshell is inside the 4s subshell. 4s electrons feel a more or less constant Z*. Sizes stay about the same and chemistries are similar! Dr. S. M. Condren

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**Density of Transition Metals**

6th period 5th period 4th period Dr. S. M. Condren

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**Ion Sizes Does the size go**

up or down when losing an electron to form a cation? Dr. S. M. Condren

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**Ion Sizes CATIONS are SMALLER than the atoms from which they come.**

Li + , 78 pm 2e and 3 p Forming a cation. Li,152 pm 3e and 3p CATIONS are SMALLER than the atoms from which they come. The electron/proton attraction has gone UP and so size DECREASES. Dr. S. M. Condren

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Ion Sizes Does the size go up or down when gaining an electron to form an anion? Dr. S. M. Condren

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**Ion Sizes ANIONS are LARGER than the atoms from which they come.**

Forming an anion. F - , 133 pm 10 e and 9 p F, 71 pm 9e and 9p ANIONS are LARGER than the atoms from which they come. The electron/proton attraction has gone DOWN and so size INCREASES. Trends in ion sizes are the same as atom sizes. Dr. S. M. Condren

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Trends in Ion Sizes Dr. S. M. Condren

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**Trends in Ionization Energy**

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2nd IE / 1st IE Li Na K B Al Dr. S. M. Condren

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**Electron Affinity A few elements GAIN electrons to form anions.**

Electron affinity is the energy involved when an atom gains an electron to form an anion. A(g) + e- ---> A-(g) E.A. = ∆E Dr. S. M. Condren

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**Electron Affinity of Oxygen**

∆E is EXOthermic because O has an affinity for an e-. [He] O atom + electron O [He] - ion EA = kJ Dr. S. M. Condren

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**Electron Affinity of Nitrogen**

[He] N atom ∆E is zero for N- due to electron-electron repulsions. + electron [He] N- ion EA = 0 kJ Dr. S. M. Condren

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**Announcements You may bring a 4x6 index card with information**

A periodic table and a table of thermodynamic data will be furnished. You need to know your TAs name and your section number. Photo ID will be required when submitting your exam. Dr. S. M. Condren

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**Announcements Last day to drop**

Suzie and Christie have papers to return, please see them after class Dr. S. M. Condren

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